The invention relates to improvements in screw couplings of the type disclosed in commonly owned U.S. Pat. No. 4,787,657 granted Nov. 29, 1988 to Dieter Henniger for "Screw Coupling". The disclosure of this patent is incorporated herein by reference. Henniger discloses a screw coupling wherein a cable, hose or a like part can be engaged by a set of prongs or tongues each having a relatively wide clamping portion extending to both sides of an axially extending web which serves to connect the clamping portion with an externally threaded portion of a nipple. The width of the clamping portions exceeds the width of the respective web, as seen in the circumferential direction of the externally threaded portion. Furthermore, the clamping portions of neighboring prongs overlie each other in the axial direction but not in the circumferential direction of the externally threaded portion. The prongs are separated from each other by slots or gaps the width of which increases in a direction away from the internally threaded section. An advantage of the patented coupling is that the clamping portions of its prongs have ample room to conform to the outline of a cable, hose or a like part while a nut is rotated to move its internal thread into mesh with the externally threaded section of a nipple including the prongs and the externally threaded section. This renders it possible to properly clamp cables, hoses or like parts having large or small diameters. Another advantage of the patented coupling is that the neighboring prongs can move relative to each other while they are being subjected to the deforming action of the nut; this ensures that each prong can adequately engage a hose, a cable or a like part without interfering with the radially inward movement of the clamping portion on the adjacent prong. This, in turn, ensures that a cable, a hose or a like part can be adequately engaged by all of the clamping portions, e.g., to establish an adequate sealing or locking action (i.e., to prevent axial movements of the patented coupling and a hose or cable relative to each other). An additional advantage of the patented coupling is that the clamping portion of each prong can be moved into large-area contact with the external surface of a cable, a hose or a like object to thus further reduce the likelihood of axial movement of the coupling and a cable or the like relative to each other and to enhance the likelihood of establishing a reliable seal between the deformed (radially inwardly flexed) portions of the prongs and the external surface of an object which is surrounded by such portions of the coupling.
The coupling of Henniger is designed in such a way that each coupling portion extends to both sides of the respective main portion. As a rule, the patented coupling is designed to ensure that the length of each clamping portion in the direction of rotation of the coupling to deform the prongs equals or at least approximates the extent to which each clamping portion projects in the opposite direction.
German Pat. No. 21 32 951 discloses a sealing sleeve which can be installed in a wall or the like and is provided with an external thread serving to mate with the internal thread of a nut to thereby deform a plastic tubular sealing element into engagement with the external surface of a hose, a cable or a like part which extends through the nut, through the sealing element and through the sleeve. The sealing element is provided with axially parallel slots and is intended to establish a fluidtight (i.e., liquid-proof as well as gas-proof) connection between the patented device and the external surface of a cable, hose or the like. The slots in the sealing element are straight and extend substantially tangentially of the internal surface of such element. The prongs of the sealing element overlap each other, not unlike the sections of a fan, in the circumferential direction of the sleeve when the nut is applied to subject the sealing element to a requisite sealing action.
German Pat. No. 26 31 996 discloses a plastic screw coupling wherein the prongs are provided with tooth-shaped sections and partially overlap each other when the internally threaded nut is applied to subject the prongs to a deforming action. The patented coupling is further provided with means for preventing accidental loosening of the nut, namely a toothed gear in the nut which is caused to mate with the tooth-shaped sections of the prongs. The internal surface of the nut is provided with an inclined internal thread which acts upon the free ends of the prongs in a sense to apply a force which acts upon successive tongues radially inwardly, i.e., toward the hose, cable or a like object which is surrounded by the patented coupling. This causes the tongues to partially overlap each other in the applied condition of the coupling, and the internal saw teeth of the nut then mate with the external saw teeth of the deformed prongs in order to prevent unintentional loosening of the nut.
German Utility Model No. 84 15 525 discloses a screw coupling which can be applied to cables hoses or like objects and wherein the prongs together form a ring. At least one of the prongs is configurated in such a way that it is driven toward the axis of the clamped object when a nut (which serves to deform the prongs) is applied. Thus, the at least one prong is moved out of the ring toward the center of the ring. In other words, all of the prongs no longer form a ring. The distribution of neighboring prongs in the coupling of the Utility Model is such that the at least one prong is acted upon by a cam face or ramp at its front and rear sides (as seen in the circumferential direction of the nut); such ramps compel the at least one prong to move out of the ring and toward the axis of the clamped object. The just described coupling can engage the surrounded object with a considerable force; however, the sealing action is unsatisfactory or nil.